Course Introduction to Matlaband Simulink Simulink/1 · Course Introduction to Matlaband Simulink Simulink/1 Emanuele Ruffaldi May11, 2017 Scuola Superiore Sant’Anna, Pisa ... solution

Course Introduction to Matlab and SimulinkSimulink/1

Emanuele RuffaldiMay 11, 2017

Scuola Superiore Sant’Anna, Pisa

https://github.com/eruffaldi/course_simulink

© 2016 Scuola Superiore Sant’Anna

Simulink Use Cases

Airbus used Model-Based Design to model the A380’s fuel management system, validate requirements through simulation, and clearly communicate the functional specification [MW]

NASA X-43A

DLR Robotics

Nissan 350Z

PERCRO BE

Doheny Eye


Simulink Features

1. Visual Programming– Defining a program by means of a graphical representation of the problem

– Alternative to Textual Programming2. Model-based Simulation– Connections to the dynamics and physics of the problems

3. From Simulation to Embedding– Code Generation– Live Connection to the Embedded Target


Simulink History

• Introduced in 1990 inside MATLAB (1984)• Real-Time Workshop (2002)• Concepts are a bit older (1968)

"Doing With Images Makes Symbols: Communicating With Computers” (1968)


Alternatives

• As concerns MATLAB there are Open Source alternatives with similar capabilities (Python+packages, Julia, SciLab) or clones (Octave).

• As concerns Simulink the most similar solution is Scicos (INRIA), while Ptolemy II (Berkeley) is worth mentioning


Simulink Material

• Inside MATLAB– doc simulink

• Online PDF (3000 pages)• Online Web


Simulink Concepts

• System, Block, Signals• Execution Modes• Sampling Time• Scopes and Logging


Starting Simulink

• From MATLAB command line• simulink• From Toolbar (version dependent)

• Opening Simulink SLX/MDL file• Command line for opening a model– modelname– Open_system(‘modelname’)


Simulink Model Window (Design)

Usual New/Open/Save

Simulation Duration (seconds or Inf)

Execution Mode

Show values Debug

Model Browser

Model Explorer

Library Browser

Zoom Integrator

Play/Stop


Visual Programming

A B

What does it mean?

This is an example of Dataflow/Graph based Visual Programming that is alternative to the approach called Block Visual Programmingas used in Scratch (MIT)


Simulink Block

BlockInput u(t) Output y(t)State x(t)

Parameters

(time)

Example of minimal plot of sinus


Nature of a Simulink Block

Enabler

Input

Output

Label

INSIDE

OUTSIDE

SampleTime

State

Parameters Costant/Tunable

Discrete/ContinuousType of sampling time

Trigger


Simulink Block and Lines

• Blocks are computational units• Blocks can be non-virtual and virtual• Blocks are connected by lines• Lines have the meaning of signals

• Signals are• Typed / Loggable / Viewable

• A Simulink system describes the time-based relationship between blocks and their signals


Block Types

• Source – generates data• Sink – receives data• Virtual Block – deals with logical structure• Subsystem – aggregation of blocks (real or virtual)• Custom Blocks (S-Functions) – C or M-code based

Source Output y(t)

SinkInput u(t)

BlockInput u(t) Output y(t)

Plot, Store, Send to Network …, Goto

Load from File, Workspace, CurveConstant, …, Label, From Network …


Simulink Data Types

• Defined at Start of Simulation• Types– float/double– various integers: [u]int8/16/32– fixed types– boolean– enumeration– structures (BUS next lecture)

• Dimensionality: from scalar to matrices• Conversion is possible


Example Data TypesEnter “datatypedemo” at the MATLAB command window


Signal Routing

• Signals can be routed– Mux/Demux– From/GoTo– Switch– Selection


Simulink Library Browser

Search Block by Name and Description

Block list

Description

Library Tree

New Model (CTRL+N)

The library browser manages the available blocks

Explore it for understanding and finding solutions


Library Browser along Lectures


Building a Model

Drag and Drop blocks from Library Browser

or activate context menu of block and select “Add to …”


Manipulating Blocks

• Selection• Multiple Selection with Shift• Multiple Selection with Box Selection

• Clone• Drag with CTRL

• Move Blocks• Drag• Rotate (CTRL+R)

• Connect Blocks• Select first and select second using CTRL/CMD• Branch line by holding CTRL from an existing line• Disconnect block by drag a block holding SHIFT


Simulation

• Execution of the Simulation from startTime to stopTime times• Expressed in simulation seconds• Can be an expression• Can be up to Infinity (Inf)• Can be stopped by the “Stop Block”

• Simulation is decomposed in Time Steps as Fixed or Variable steps


Running a Model

Pause/Stop

Current TimeStatus Integration Time

• Ex: Play with time step min/max• Try other function generators


Invoking Simulation from Matlab

• The “sim” command allows to run a model from MATLAB changing parameters and input data– sim(modelname,param,paramvalue…)– sim(modelname,struct)

• Example Options– SimulationMode– SaveState– StateSaveName

• The model(..) command allows for finer control of the Simulation


Looking at Results

• Insert Scope/Floating Scope/XY Graph• Context menu: Create and Connect Viewer

• Use Signal selector for modifying the signal

Signal selector

AutozoomZoom

Parameters

Properties


Bouncing Ball - Integrator

• Integrates a differential equation

• Inputs and Ports– Input (always)– Reset– Initial Condition– Saturation– State


Bouncing Ball

• This is an example of Continuous System with Simulink


Bouncing Ballsldemo_bounce_two_integrators


Heat Example

• From Mathworks website• https://it.mathworks.com/help/simulink/gs/define-system.html?s_cid=learn_doc


Bacteria Example

• Birth rate = b x– b = 1/hour

• Death rate = p x2– p=0.5


Exercise

• Create a 2D source (e.g. sin wave and )• Compute the polar coordinates (modulus and angle) and plot them


Exercise

• Cannon Dynamics with bouncing• Ballistics with air resistance (1D)– Fd = -D v|v|– F = Fd – mg = ma

• Parameters– m=0.145kg– D=0.02– x0=(0,0)– v0=(0.1,0.2) m/s


Exercise/2

• Based on the previous Simulation modify the initial conditions from Matlab and use the “sim” function to execute the simulation and collect the final end position


Reference of Blocks in this Lecture

IC (initial value)Signal Attributes

Mux/DeMuxSignal Routing

SwitchSignal Routing

From/GoToSignal Routing

SelectorSignal Routing

ScopeSinks

DisplaySinks

STOPSinks

To WorkspaceSinks


Reference of Blocks in this Lecture / 2

ConstantSources

GroundSources

Sine WaveSources

ClockSources

IntegratorContinuous

ComparisonLogical

GainMath

Product/SumMath

From WorkspaceSources

TrigonometricMath

SQRTMath

Course Introduction to Matlaband Simulink Simulink/1 · Course Introduction to Matlaband Simulink Simulink/1 Emanuele Ruffaldi May11, 2017 Scuola Superiore Sant’Anna, Pisa ... solution

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